Ionising nuclear radiation can cause mutations in living organisms through the direct and indirect damage it inflicts on DNA. Direct damage occurs when the radiation directly breaks chemical bonds within the DNA molecule, such as the bonds holding the sugar-phosphate backbone together or damaging the bases themselves. Indirect damage occurs when the radiation interacts with water molecules, which are abundant in cells. This interaction produces highly reactive free radicals (e.g., hydroxyl radicals). These free radicals can then attack the DNA, causing damage to the bases and the DNA strands.

The damage to DNA can manifest in several ways, including:

• Base alterations: Radiation can alter the chemical structure of DNA bases, causing them to mispair during DNA replication. For example, thymine can be converted to cytosine.
• Strand breaks: Radiation can cause single-strand or double-strand breaks in the DNA molecule.
• Insertions or deletions: During DNA repair, errors can occur, leading to the insertion or deletion of DNA bases.

These mutations can alter the genetic code, leading to changes in the protein produced by the gene, and potentially causing harmful effects on the organism.

Radioactive materials require stringent safety measures throughout their lifecycle – from production to disposal. Safe handling begins with transportation. Radioactive materials are typically packaged in robust, shielded containers designed to withstand accidents and prevent the escape of radiation. These containers are often labelled with internationally recognised hazard symbols. Transportation routes are carefully planned to minimise public exposure and potential risks. Regulations govern the type of transport vehicle and the accompanying security measures.

Use of radioactive materials is carefully controlled and typically takes place within designated facilities, such as hospitals, research laboratories, and power plants. Shielding is a crucial aspect of safe use. This can involve using materials like lead or concrete to absorb radiation. Remote handling equipment, such as robotic arms, is often employed to minimise direct human contact with radioactive sources. Strict protocols are in place to limit exposure times and monitor radiation levels. Personnel working with radioactive materials undergo thorough training in radiation safety procedures.

Storage of radioactive materials is also highly regulated. Materials are typically stored in secure, shielded areas designed to prevent unauthorised access and contain any potential leaks. Storage facilities are often located deep underground or within specially constructed buildings with reinforced concrete walls. The type of container used for storage depends on the nature of the radioactive material and its half-life. Long-term storage may involve specialized repositories designed to isolate the materials from the environment for thousands of years. Regular monitoring of storage areas is essential to detect any signs of leakage or deterioration. Waste is segregated based on its radioactivity level and disposed of according to specific regulations.

Precautions to protect people and the environment include:

• Shielding: Using materials like lead or concrete to absorb radiation.
• Containment: Employing sealed containers and facilities to prevent the release of radioactive materials.
• Monitoring: Regularly measuring radiation levels to ensure safety.
• Training: Providing comprehensive training to personnel handling radioactive materials.
• Waste Disposal: Following strict regulations for the safe disposal of radioactive waste.

When working with Cobalt-60, a scientist must implement several safety precautions to minimise radiation exposure. Here are three specific examples:

1. Shielding: The Cobalt-60 source should be housed within a lead-lined enclosure. Lead is an effective absorber of gamma radiation, which is emitted by Cobalt-60. The enclosure should be of sufficient thickness to attenuate the radiation to safe levels. The scientist should always work behind this shielding when handling the source.
2. Distance: Maintaining a greater distance from the Cobalt-60 source significantly reduces the intensity of the radiation received. The scientist should use long-handled tools or remote manipulators to handle the source, avoiding direct contact. The further away the scientist is, the lower the radiation dose.
3. Time: The duration of exposure to radiation should be minimised. The scientist should plan their work carefully to complete tasks quickly and efficiently. They should avoid unnecessary handling of the Cobalt-60 source. Using automated equipment or pre-prepared solutions can help reduce exposure time.